1. Field of the Invention
The present invention relates to a mast assembly and method and, in particular embodiments, a deployable and retractable, telescoping style mast assembly and method.
2. Related Art
Mast structures are designed to provide necessary strength and/or stiffness in applications requiring beam, cantilever, or column support. Mast structures are used in a variety of contexts, such as for supporting equipment or other structures at a distance from the body of a space craft, as support structures in various Earth based or water based vehicles or structures and as antennae structures, to name a few. Deployable type of mast structures combine these capabilities with a low stowable volume and the ability to actuate or deploy as required.
One method for constructing a deployable mast incorporates the telescoping tube concept. Telescoping tube type mast structures are widely used for existing nonspace application. For example, typical automobile antennae structures employ telescoping tube type masts. Such telescoping tube structures employ a number of segmented tube lengths which nest within each other. In the stowed state, the total length of the telescoping mast is generally the length of the outermost tube segment. In the deployed state, the total length equals the sum of each segment length minus the overlap between the tube segments. This overlap provides the means for reliable deployment and/or retraction, and with the tubes latched to each other, the overlap insures the capability to carry bending loads. In addition, if the tip deflection due to dead band is to be minimized, the gap space between the inner and out tubes must be small.
In certain applications, various conventional mast structures may be inadequate. For example, many conventional mast structures may be too large or heavy for certain applications or may be too easily collapsed or retracted under their own weight, external forces, or damage from impacting particles. For certain aerospace applications, where considerable importance is placed on size, mass, packaging size, the ability to restow, or damage tolerance, the tubes must have a minimal overlap and a reliable redundant mechanism to latch the mast in a deployed state and unlatch the mast for retraction. Additionally for certain applications, minimizing tube overlap reduces weight.